Fuel



Patented July 30, 1935 FUEL Paul L. Salzbcrg and Wesley R. Peterson, Wilmington, Del., assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application December 6, 1932, Serial No. 645,944

3 Claims.

This invention relates to improvements in compression ignition fuels and it particularly relates to novel ignition accelerators for such fuels.

One object of this invention relates to improve- 5 ments in Diesel engine fuels and particularly in fuels adapted for use in high-speed compression ignition engines whereby to obtain a reduction of the delay period between the injection and the ignition of the fuel, a reduction in the ignition temperature of the fuel and/or a lowering of the compression ratio of the engine. A specific object relates 'to compression ignition fuels containing organic compounds having nitroso or oxime groups. Other objects of the invention will become apparent from the following description.

In accordance with the present invention, it has been found that when organic compounds containing either a nitroso or an oxime group are dissolved in fuel oil of the Diesel engine type, there is obtained a reduction in the delay period between injection and ignition of the fuel oil, this phenomenon being accomplished by a lowering of the ignition temperature of the fuel oil and/or a lowering of the compression ratio in the com pression engine required to ignite the fuel. Organic nitroso compounds and oximes are soluble to a substantial extent in Diesel engine fuel.

The following table illustrates examples of aliphatic compounds containing either a nitroso or an oxime group which may be used in accordance with the practice of the invention. This table also illustrates the efiect of the use of these compounds on the fuel oil characteristics, the properties of the doped or modified fuel oil being compared with those of unmodified fuel oil, the same quality of fuel oil being used in all of the examples:

where R and R1 are aliphatic radicals, e. g., alkyl or alkylene radicals.

secondary amino radical, e. g.,- piperidine, morpholine, pyrrolidine or a carbazole radical.

ignition temperature is the lowest temperature at which a majority of a series of samples injected into the chamber ignite. pression ratio was determined according to the method described by Pope and Murdock in the 5 Society of Automotive Engineers Journal, Transactions pages 136-142 for March 1932.

The minimum com- The structure and constitution of the nitroso compounds and of the oximes are capable of considerable modification, e. g., they may be either 10 aliphatic or hetero-cyclic, the oximes may be aldoximes or ketoximes, etc.

The following classes include the compounds which may be used in accordance with the present invention: 5

where R, R1, and R2 are hydrocarbon radicals, e. g., alkyl radicals as in trimethyl nitroso methane.

3. R=NN=O where R=N represents a cyclic Composition fuel Accelerator Minimum compression ratio Minimum ignition temp.

At 514 C.

+5% by wt. n-Butyml ioxime Saturated with n-nitroso carhazole +24% by wt. nitroso-dimethyl amine +5% by wt. nilroso-dlbutyl amine +33% by wt. n-Hcptnldoxime Saturated with cyclohexanone oximo Saturated with dimetliyglyoxime where R and R1 are hydrogen or hydrocarbon The method of test for determining the ignition delay and minimum ignition temperature consisted in injecting the fuel oil into air at atmospheric pressure into a heated chamber. The ignition delay is the elapsed time between injection and ignition of the fuel. The minimum radicals, e. g., alkyl or alkylene radicals.

6. R=C=NOH where R is the hydrocarbon N H NOH where n is zero or any small whole number and R and R1 are hydrogen or an aliphatic radical, e. g., alkyl or alkvlene.

The term aliphatic radical, as used herein and in the claims, refers to aliphatic groups that do not contain an aromatic radical.

Specific examples of compounds under 1) above are: nitroso-dimethyl amine, nitroso-dibutyl amine, nitroso-diisopropyl amine, nitrosomethyl butyl amine, nitroso-vinyl methyl amine, and nitroso-diisobutyl amine.

Specific examples of (2) above are: tertiary nitroso compounds such as trimethyl nitroso methane, nitroso tertiary heptane, and nitroso tertiary octane.

Specific examples of (3) above are: nitrosopiperidine, N-m'troso carbazole, nitroso pyrrolidine and nitroso morpholine.

A specific example of compounds under (4) above is dinitroso piperazine.

Specific examples of compounds under (5) above are: Formaldoxime, acetaldoxime, butyraldoxime, isobutyraldoxime, heptaldoxime, acroleinoxime, acetoxime, methyl ethyl ketoxime (2,2- dimethyl butanoxime-3) methyl hexyl ketoxime and methyl isopropyl ketoxime.

Specific examples of compounds under (6) above are: cyclohexanoneoxime, cyclopentanoneoxime, l-methyl cyclopentanoneoxime, and cycloheptanoneoxime.

Specific examples of compounds under ('7) above are: glyoxime, methyl glyoxime, dimethyl glyoxime, propan-dioxime-1,3, and pentane dioxime-1,3.

The proportion of ignition accelerator to be added to the fuel may range from a fraction of one per cent up to the limit of solubility in the fuel.

The advantages of the use of these accelerators in fuel oil for compression ignition engines are:

1. Elimination of knocking and rough-running by decreasing the ignition lag.

2. Reduction of engine wear by removing the cause of knocking and roughness.

3. Easier starting. The reduced spontaneous ignition temperatures of the doped oil enables it to ignite much more easily when starting from cold.

4. Improved exhaust. Owing to the more complete combustion the exhaust is cleaner especially at higher speeds. No harmful constituents are introduced into the exhaust gases by the combustion of the dope.

5. Possibility of use of inferior fuels. By the addition of dope, low grade fuels, at present quite unsuitable for compression ignition engines, can be rendered equal or superior to high grade undoped fuels.

6. Nature of dope. The dope has a neutral reaction, is non-toxic and soluble in the oil.

7. Improvements in engine design. Reduced engine stresses, resulting from the more gradually applied piston pressures, should make for lighter scantlings while the more readily ignited and rapidly burning fuel should render possible the construction of smaller and faster runningengines.

8. Increased power and reduced fuel consumption. The improved combustion resulting from the explosive action of the dope enables a greater proportion of the air charge to be burnt, and 5 further, as ignition takes place at once, the fuel can be injected during the compression stroke at a. smaller crank angle near top dead center.

The specific advantages of the invention over the prior art result from decreased vapor pressure of the nitroso derivatives of aliphatic or heterocyclic secondary amines, the aldoximes and ketoximes, and from the nonexplosive nature of the compounds. The boiling point of a few compounds used as fuel dopes, including those of the present invention, are given in the following table:

Dope Boiling point Melting point Methyl nitrate Ethyl nitrate N itroso-dimethyl amine. N itroso-dibutyl amine N-nitroso carbazole n-B utyraldoxime n-Heptaldoxime Cyclohexanoneoxime Dimethylglyoxime (solid).

Further advantages are:

1. The increased boiling point prevents the formation of vapor locks in the fuel system of the engine.

2. Elimination of hazard in transportation and storage. Thedecreased vapor pressures eliminate the possibility of the formation of an explosive, dope-air mixture above the fuel in tank cars or storage tanks.

3. Decrease in objectionable physiological properties. The decreased vapor pressure of the dopes also decreases the physiological effects, such as headaches, which constitute an objection to the nitric esters of alcohols.

The above description and examples are to be taken as illustrative only and not as limiting the scope of the invention. Any modification or variation therefrom which conforms to the spirit of the invention is intended to be included within the scope of the claims.

We claim:

1. A compression ignition fuel comprising an oil boiling above the gasoline range containing a compound having a type formula Where R and R1 are aliphatic radicals.

2. A compression ignition fuel comprising an oil boiling above the gasoline range containing nitroso-dimethyl amine.

3. A compression ignition fuel comprising an oil boiling above the gasoline range containing nitroso-dibutyl amine.

PAUL L. SALZBERG. WESLEY R. PETERSON. 

